20% out of 70 plants
2 answers:
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Answer:
The number of seat when n is odd
The number of seat when n is even
Step-by-step explanation:
Given that, each successive row contains two fewer seats than the preceding row.
Formula:
The sum n terms of an A.P series is
a = first term of the series.
d= common difference.
n= number of term
l= last term
term of a A.P series is
n is odd:
n,n-2,n-4,........,5,3,1
Or we can write 1,3,5,.....,n-4,n-2,n
Here a= 1 and d = second term- first term = 3-1=2
Let of the series is n.
Here , n=t, a=1 and d=2
⇒(t-1)2=n-1
Last term l= n,, the number of term , First term = 1
Total number of seat
n is even:
n,n-2,n-4,.......,4,2
Or we can write
2,4,.......,n-4,n-2,n
Here a= 2 and d = second term- first term = 4-2=2
Let of the series is n.
Here , n=t, a=2 and d=2
⇒(t-1)2=n-2
Last term l= n, the number of term , First term = 2
Total number of seat